In a wire harness installed in a vehicle such as an automobile, it is common to form a splice portion by partially stripping away the coverings of insulated sheathed electrical lines to partially expose the conductors (core lines) made up of conductor element wires, and then join the exposed conductor portions using a crimping terminal or ultrasonic welding. Also, in the case where waterproofing is required, such as the case where the splice portion is arranged in a water-exposed region in a vehicle, a waterproof structure that prevents corrosion of the splice portion is provided.
As a conventional waterproof structure of this type, there is known to be, for example, a waterproof structure in which tape with a thermal foaming adhesive material applied thereon is wrapped around a pair of sheathed end portions on the trunk line side from which the covering in an intermediate portion has been stripped and a sheathed end portion on the branch line side that is to be joined to the intermediate portion, and a waterproof sheet is cylindrically wrapped around and adhered to the sheathed end portions and the splice portion from the outside (e.g., see JP H7-245842A).
Also, there is known to be a technique in which the exposed conductor portions in intermediate portions of a pair of insulated sheathed electrical lines are joined together, a water sealant is applied around them, then the splice portion is covered with a flexible and light-permeable protective sheet, and the water sealant is brought into close contact with the periphery of the splice portion by applying appropriate tensile force to the protective sheet, for example, while causing the protective sheet to following the contraction during the light curing of the water sealant (e.g., see JP 2012-80633A).
JP H7-245842A and JP 2012-80633A are examples of related art.
However, in the former conventional wire harness waterproof structure that uses tape with a thermal foaming adhesive material applied thereon as described above, there is an unresolved issue in that if the amount of thermal foaming adhesive material is too high, it is likely to leak out from the two end portions of the cylindrical waterproofing sheet, but if the amount of thermal foaming adhesive material is too low, it is not possible for the thermal foaming adhesive material to reach the splice portion side.
Also, in the latter conventional wire harness waterproof structure in which a flexible protective sheet is used and caused to follow the deformation during curing of the water sealant, there is an unresolved issue in that even if the protective sheet is light-permeable, it is not possible to easily visually check from outside the protective sheet whether or not the water sealant has reliably penetrated into the spaces between the element wires, for example, or whether or not the water sealant has penetrated into the spaces between the end portions of the covering and the core line made up of a group of conductor element wires.
For this reason, conventionally, unless the waterproofing section in the vicinity of the splice portion is lengthened and the water sealant filling amount is set high, there is a possibility of water entering the splice portion in the case where the splice portion is arranged in a water-exposed area in the vehicle, for example. Also, it has not been possible to avoid the issue that once water has entered the splice portion covered by the waterproofing sheet, it is difficult for the water to be drained.
The present invention was achieved in order to solve conventional issues such as those described above, and an object thereof is to provide a wire harness waterproof structure that enables the water sealant filling state in the periphery of the splice portion to be easily visually checked from outside the protective sheet or the like, that enables reliably filling the periphery of the splice portion with the water sealant without using a large amount of water sealant, and also enables water that has entered an unfilled region to be easily drained.